Effect of boron application time on yield of wheat, rice and cotton crop in Pakistan

Boron (B), one of the essential micronutrients, plays vital role in plant growth. Thirty one field experiments were conducted to evaluate the response of wheat, rice and cotton to B application throughout Pakistan during 2005-08. Boron was applied at 1 kg ha^-1 as Borax decahydrate (11.3% B) at different times along with recommended doses of N, P and K. The results revealed that B application at sowing time to wheat increased significantly the number of tillers plant^-1 (15%), number of grains spike^-1 (11%), 1000-grain weight (7%) and grain yield (10%) over control. Among the treatments, B application at sowing time showed best results followed by B application at 1st irrigation and at booting stage. In rice (coarse), B application before transplanting substantially increased number of tillers hill^-1 (21%), plant height (3%), panicle length (10%), and number of paddy grains panicle^-1 (17%), 1000-grain weight (11%) and paddy yield (31%) over control. Response of fine rice to B application was similar for all yield parameters as in coarse rice. In cotton, B application considerably increased plant height (3%), number of mature bolls plant^-1 (12%), seed weight boll-1 (8%) and seed cotton yield (9%) over control. Although, B application at all stages significantly increased yield parameters tested but B application at sowing time was best among all treatments.